Method of manufacture of a linear spring electromagnetic grill ink jet printer

ABSTRACT

This patent describes a method of manufacturing a linear spring electromagnetic grill ink jet print head wherein an array of nozzles are formed on a substrate utilising planar monolithic deposition, lithographic and etching processes. Multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer. The print heads can be formed utilising standard VLSIULSI processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate plane.

CROSS REFERENCES TO RELATED APPLICATIONS

The following co-pending US patent applications, identified by their US patent application serial numbers (USSN), were filed simultaneously to the present application on July 10, 1998, and are hereby incorporated by cross-reference: 09/113,060; 09/113,070; 09/113,073; 09/112,748; 09/112,747; 09/112,776; 09/112,750; 09/112,746; 09/112,743; 09/112,742; 09/112,741; 09/112,740; 09/112,739; 09/113,053; 09/112,738; 09/113,067; 09/113,063; 09/113,069; 09/112,744; 09/113,058; 09/112,777; 09/113,224; 09/112,804; 09/112,805; 09/113,072; 09/112,785; 09/112,797; 09/112,796; 09/113,071; 09/112,824; 09/113,090; 09/112,823; 09/113,222; 09/112,786; 09/113,051; 09/112,782; 09/113,056; 09/113,059; 09/113,091; 09/112,753; 09/113,055; 09/113,057; 09/113,054; 09/112,752; 09/112,759; 09/112,757; 09/112,758; 09/113,107; 09/112,829; 09/112,792; 09/112,791; 09/112,790; 09/112,789; 09/112,788; 09/112,795; 09/112,749; 09/112,784; 09/112,783; 09/112,763; 09/112,762; 09/112,737; 09/112,761; 09/113,223; 09/112,781; 09/113,052; 09/112,834; 09/113,103; 09/113,101; 09/112,751; 09/112,787; 09/112,802; 09/112,803; 09/113,097; 09/113,099; 09/113,084; 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821; 09/112,822; 09/112,825; 09/112,826; 09/112,827; 09/112,828; 09/113,111; 09/113,108; 09/113,109; 09/113,123; 09/113,114; 09/113,115; 09/113,129; 09/113,124; 09/113,125; 09/113,119; 09/113,120; 09/113,221; 09/113,116; 09/113,118; 09/113,117; 09/113,113; 09/113,130; 09/113,110; 09/113,112; 09/113,087; 09/113,074; 09/113,089; 09/113,088; 09/112,771; 09/112,769; 09/112,770; 09/112,817; 09/113,076; 09/112,798; 09/112,801; 09/112,800; 09/112,799; 09/113,098; 09/112,833; 09/112,832; 09/112,831; 09/112,830; 09/112,836; 09/112,835; 09/113,102; 09/113,106; 09/113,105; 09/113,104; 09/112,810; 09/112,766; 09/113,085; 09/113,086; 09/113,094; 09/112,760; 09/112,773; 09/112,774; 09/112,775; 09/112,745; 09/113,092; 09/113,100; 09/113,093; 09/113,062; 09/113,064; 09/113,082; 09/113,081; 09/113,080; 09/113,079; 09/113,065; 09/113,078; 09/113,075.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to the manufacture of ink jet print heads and, in particular, discloses a method of manufacture of a Linear- Spring, Electromagnetic-Grill Ink Jet Printer.

BACKGROUND OF THE INVENTION

Many ink jet printing mechanisms are known. Unfortunately, in mass production techniques, the production of ink jet heads is quite difficult. For example, often, the orifice or nozzle plate is constructed separately from the ink supply and ink ejection mechanism and bonded to the mechanism at a later stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)). These separate material processing steps required in handling such precision devices often add a substantial expense in manufacturing.

Additionally, side shooting ink jet technologies (U.S. Patent No. 4,899,181) are often used but again, this limits the amount of mass production throughput given any particular capital investment.

Additionally, more esoteric techniques are also often utilised. These can include electroforming of nickel stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)), electro-discharge machining, laser ablation (U.S. Patent No. 5,208,604), micro-punching, etc.

The utilisation of the above techniques is likely to add substantial expense to the mass production of ink jet print heads and therefore add substantially to their final cost.

It would therefore be desirable if an efficient system for the mass production of ink jet print heads could be developed.

SUMMARY OF THE INVENTION

It is an object of present invention to provide an alternative form of ink jet printing.

In accordance with a first aspect of the present invention, there is provided a method of manufacturing a linear spring electromagnetic grill ink jet print head wherein an array of nozzles are formed on a substrate utilising planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilising standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably are of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.

In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: (a) utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon; (b) etching a nozzle chamber aperture in the electrical circuitry layer interconnected with a nozzle chamber in the semiconductor wafer; (c) depositing a first sacrificial layer filling the nozzle chamber; (d) depositing and etching an inert material layer including a grill structure over the nozzle chamber aperture and vias for electrical interconnection of subsequent layers with the electrical circuitry layer; (e) depositing and etching a first conductive material layer including a series of lower electrical coil portions interconnected with the electrical circuitry layer; (f) depositing and etching an inert material layer over the first conductive material layer, the inert material layer including predetermined vias for interconnection of the first conductive material layer with subsequent layers; (g) depositing and etching a second sacrificial layer including etching a mould for a solenoid, a fixed magnetic pole, and a linear spring anchor; (h) depositing and etching a high saturation flux material layer to form the series of fixed magnetic poles, a linear spring, the linear spring anchor and an interconnected shutter grill; (i) depositing and etching a second inert material layer over the high saturation flux material layer including predetermined vias for interconnection of lower layers with subsequent layers; 0) depositing and etching a second conductive material layer including side electrical coil portions surrounding the series of fixed magnetic poles interconnected with the first conductive material layer; (k) depositing and etching a third conductive material layer including a top electrical coil portion interconnected with the side conductive material layer; (1) depositing and etching a top inert material layer as a corrosion barrier; (m) back etching the wafer to the epitaxial layer; (n) etching a nozzle aperture in the epitaxial layer; and (o) etching away the sacrificial layers.

The epitaxial layer can be utilized as an etch stop in the step (b) which can comprise a crystallographic etch of the wafer.

The high saturation flux material can comprise substantially a cobalt nickel iron alloy and the conductive layers can comprise substantially copper with the inert layers comprising substantially silicon nitride.

The steps are preferably also utilized to simultaneously separate the wafer into separate printheads.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings which:

FIG. 1 is a perspective view of a single ink jet nozzle constructed in accordance with the preferred embodiment, in its closed position;

FIG. 2 is a perspective view of a single ink jet nozzle constructed in accordance with the preferred embodiment, in its open position;

FIG. 3 is a perspective, cross-sectional view taken along the line I—I of FIG. 2, of a single ink jet nozzle in accordance with the preferred embodiment;

FIG. 4 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with the preferred embodiment;

FIG. 5 provides a legend of the materials indicated in FIGS. 6 to 27; and

FIG. 6 to FIG. 27 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the present invention, a magnetically-actuated ink jet print nozzle is provided for the ejection of ink from an ink chamber. The magnetically actuated ink jet utilises a linear spring to increase the travel of a shutter grill which blocks any ink pressure variations in a nozzle when in a closed position.

However when the shutter is open, pressure variations are directly transmitted to the nozzle chamber and can result in the ejection of ink from the chamber. An oscillating ink pressure within an ink reservoir is used therefore to eject ink from nozzles having an open shutter grill.

In FIG. 1, there is illustrated a single nozzle mechanism 10 of the preferred embodiment when in a closed or rest position. The arrangement 10 includes a shutter mechanism 11 having shutters 12, 13 which are interconnected together at part 15 at one end for providing structural stability. The two shutters 12, 13 are interconnected at another end to a moveable bar 16 which is further connected to a stationary positioned bar 18 via leaf springs 20, 21. The movable bar 16 can be made of a soft magnetic (NiFe) material.

An electromagnetic actuator is utilised to attract the movable bar 16 generally in the direction of arrow 25. The electromagnetic actuator consists of a series of soft iron claws 24 around which is formed a copper coil wire 26. The electromagnetic actuators can comprise a series of actuators 28-30 interconnected via the copper coil windings. Hence, when it is desired to open the shutters 12-13 the coil 26 is activated resulting in an attraction of bar 16 towards the electromagnets 28-30. The attraction results in a corresponding interaction with linear springs 20, 21 and a movement of shutters 12, 13 to an open position as illustrated in FIG. 2. The result of the actuation is to open portals 32, 33 into a nozzle chamber 34 thereby allowing the ejection of ink through an ink ejection nozzle 36.

The linear springs 20, 21 are designed to increase the movement of the shutter as a result of actuation by a factor of eight. A one micron motion of the bar towards the electromagnets will result in an eight micron sideways movement. This dramatically improves the efficiency of the system, as any magnetic field falls off strongly with distance, while the linear springs have a linear relationship between motion in one axis and the other. The use of the linear springs 20, 21 therefore allows the relatively large motion required to be easily achieved.

The surface of the wafer is directly immersed in an ink reservoir or in relatively large ink channels. An ultrasonic transducer (for example, a piezoelectric transducer), not shown, is positioned in the reservoir. The transducer oscillates the ink pressure at approximately 100 KHz. The ink pressure oscillation is sufficient that ink drops would be ejected from the nozzle were it not blocked by the shutters 12, 13. When data signals distributed on the print head indicate that a particular nozzle is to eject a drop of ink, the drive transistor for that nozzle is turned on. This energises the actuators 28-30, which moves the shutters 12, 13 so that they are not blocking the ink chamber. The peak of the ink pressure variation causes the ink to be squirted out of the nozzle. As the ink pressure goes negative, ink is drawn back into the nozzle, causing drop break-off. The shutters 12, 13 are kept open until the nozzle is refilled on the next positive pressure cycle. They are then shut to prevent the ink from being withdrawn from the nozzle on the next negative pressure cycle.

Each drop ejection takes two ink pressure cycles.

Preferably half of the nozzles should eject drops in one phase, and the other half of the nozzles should eject drops in the other phase. This minimises the pressure variations which occur due to a large number of nozzles being actuated.

The amplitude of the ultrasonic transducer can be further altered in response to the viscosity of the ink (which is typically affected by temperature), and the number of drops which are to be ejected in a current cycle. This amplitude adjustment can be used to maintain consistent drop size in varying environmental conditions.

In FIG. 3, there is illustrated a section taken through the line I—I of FIG. 2 so as to illustrate the nozzle chamber 34 which can be formed utilising an anisotropic crystallographic etch of the silicon substrate. The etch access through the substrate can be via the slots 32, 33 (FIG. 2) in the shutter grill.

The device is manufactured on <100> silicon with a buried boron etch stop layer 40, but rotated 450 in relation to the <010> and <001> planes. Therefore, the <111> planes which stop the crystallographic etch of the nozzle chamber form a 45° rectangle which superscribes the slots in the fixed grill. This etch will proceed quite slowly, due to limited access of etchant to the silicon. However, the etch can be performed at the same time as the bulk silicon etch which thins the bottom of the wafer.

In FIG. 4, there is illustrated an exploded perspective view of the various layers formed in the construction of an ink jet print head 10. The layers include the boron doped layer 40 which acts as an etch stop and can be derived from back etching a silicon wafer having a buried epitaxial layer as is well known in Micro Electro Mechanical Systems (MEMS). For a general introduction to a micro-electro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field. The nozzle chamber side walls are formed from a crystallographic etch of the wafer 41 with the boron doped layer 40 being utilised as an etch stop.

A subsequent layer 42 is constructed for the provision of drive transistors and printer logic and can comprise a two level metal CMOS processing layer 42. The CMOS processing layer is covered by a nitride layer 43 which includes portions 44 which cover and protect the side walls of the CMOS layer 42. The copper layer 45 can be constructed utilising a dual damascene process. Finally, a soft metal (NiFe) layer 46 is provided for forming the rest of the actuator. Each of the layers 44, 45 are separately coated by a nitride insulating layer (not shown) which provides passivation and insulation and can be a standard 0.1 μm process.

The arrangement of FIG. 1 therefore provides an ink jet nozzle having a high speed firing rate (approximately 50 KHz) which is suitable for fabrication in arrays of ink jet nozzles, one along side another, for fabrication as a monolithic page width print head.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:

1. Using a double sided polished wafer 50 deposit 3 microns of epitaxial silicon heavily doped with boron.

2. Deposit 10 microns of epitaxial silicon 41, either p-type or n-type, depending upon the CMOS process used.

3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer 50 at this step are shown in FIG. 6. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 5 is a key to representations of various materials in these manufacturing diagrams, and those of other cross-referenced, ink jet configurations.

4. Etch the CMOS oxide layers 41 down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber 34, and the edges of the print head chips. This step is shown in FIG. 7.

5. Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in FIG. 8.

6. Deposit 12 microns of sacrificial material. Planarize down to oxide using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in FIG. 9.

7. Deposit 0.5 microns of silicon nitride (Si₃N₄) 52.

8. Etch nitride 52 and oxide down to aluminum 42 or sacrificial material 51 using Mask 3. This mask defines the contact vias from the aluminum electrodes to the solenoid, as well as the fixed grill over the nozzle cavity. This step is shown in FIG. 10.

9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

10. Spin on 2 microns of resist 53, expose with Mask 4, and develop. This mask defines the lower side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in FIG. 11.

11. Electroplate 1 micron of copper 54. This step is shown in FIG. 12.

12. Strip the resist 53 and etch the exposed copper seed layer. This step is shown in FIG. 13.

13. Deposit 0.1 microns of silicon nitride.

14. Deposit 0.5 microns of sacrificial material 56.

15. Etch the sacrificial material 56 down to nitride 52 using Mask 5. This mask defines the solenoid, the fixed magnetic pole, and the linear spring anchor. This step is shown in FIG. 14.

16. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)].

17. Spin on 3 microns of resist 57, expose with Mask 6, and develop. This mask defines all of the soft magnetic parts, being the U shaped fixed magnetic poles, the linear spring, the linear spring anchor, and the shutter grill. The resist acts as an electroplating mold. This step is shown in FIG. 15.

18. Electroplate 2 microns of CoNiFe 58. This step is shown in FIG. 16.

19. Strip the resist 57 and etch the exposed seed layer. This step is shown in FIG. 17.

20. Deposit 0.1 microns of silicon nitride (Si₃N₄).

21. Spin on 2 microns of resist 59, expose with Mask 7, and develop. This mask defines the solenoid vertical wire segments, for which the resist acts as an electroplating mold. This step is shown in FIG. 18.

22. Etch the nitride down to copper using the Mask 7 resist.

23. Electroplate 2 microns of copper 60. This step is shown in FIG. 19.

24. Deposit a seed layer of copper.

25. Spin on 2 microns of resist 61, expose with Mask 8, and develop. This mask defines the upper side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in FIG. 20.

26. Electroplate 1 micron of copper 62. This step is shown in FIG. 21.

27. Strip the resist 59 and 61 and etch the exposed copper seed layer, and strip the newly exposed resist. This step is shown in FIG. 22.

28. Deposit 0.1 microns of conformal silicon nitride as a corrosion barrier.

29. Open the bond pads using Mask 9.

30. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

31. Mount the wafer on a glass blank 63 and back-etch the wafer 50 using KOH with no mask. This etch thins the wafer 50 and stops at the buried boron doped silicon layer 40. This step is shown in FIG. 23.

32. Plasma back-etch the boron doped silicon layer 40 to a depth of 1 micron using Mask 9. This mask defines the nozzle rim 64. This step is shown in FIG. 24.

33. Plasma back-etch through the boron doped layer using Mask 10. This mask defines the nozzle 36, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in FIG. 25.

34. Detach the chips from the glass blank 63. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in FIG. 26.

35. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation.

36. Connect the print heads to their interconnect systems.

37. Hydrophobize the front surface of the print heads.

38. Fill the completed print heads with ink 65 and test them. A filled nozzle is shown in FIG. 27.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

The presently-disclosed, ink jet printing technology is potentially suited to a wide range of printing systems including: color and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers, high speed pagewidth printers, notebook computers with in-built pagewidth printers, portable color and monochrome printers, color and monochrome copiers, color and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic ‘minilabs’, video printers, PHOTO CD (PHOTO CD is a registered trademark of the Eastman Kodak Company) printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per print head, but is a major impediment to the fabrication of pagewidth print heads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the list above under the heading

Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems

For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mm long, with a width which depends upon the ink jet type. The smallest print head designed is United States Patent Application Serial No. 09/112,764, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The print head is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

The present invention is useful in the field of digital printing, in particular, ink jet printing. A number of patent applications in this field were filed simultaneously and incorporated by cross reference.

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. Forty-five such inkjet types were filed simultaneously to the present application.

Other ink jet configurations can readily be derived from these firty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the forty-five examples can be made into inkjet print heads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The simultaneously filed patent applications are listed by United States Patent Application Serial Numbers (USSN).. In some cases, a printer may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Thermal An electrothermal heater heats the ♦Large force generated ♦High power ♦Canon Bubblejet bubble ink to above boiling point, ♦Simple construction ♦Ink carrier limited to water 1979 Endo et al GB transferring significant heat to the ♦No moving parts ♦Low efficiency patent 2,007,162 aqueous ink. A bubble nucleates and ♦Fast operation ♦High temperatures required ♦Xerox heater-in-pit quickly forms, expelling the ink. ♦Small chip area required for ♦High mechanical stress 1990 Hawkins et al The efficiency of the process is low, actuator ♦Unusual materials required U.S. Pat. No. 4,899,181 with typically less than 0.05% of the ♦Large drive transistors ♦Hewlett-Packard TIJ electrical energy being transformed ♦Cavitation causes actuator failure 1982 Vaught et aI into kinetic energy of the drop. ♦Kogation reduces bubble formation U.S. Pat. No. 4,490,728 ♦Large print heads are difficult to fabricate Piezoelectric A piezoelectric crystal such as lead ♦Low power consumption ♦Very large area required for actuator ♦Kyser et al U.S. Pat. No. lanthanum zirconate (PZT) is ♦Many ink types can be used ♦Difficult to integrate with electronics 3,946,398 electrically activated, and either ♦Fast operation ♦High voltage drive transistors required ♦Zoltan U.S. Pat. No. expands, shears, or bends to apply ♦High efficiency ♦Full pagewidth print heads impractical 3,683,212 pressure to the ink, ejecting drops. due to actuator size ♦1973 Stemme U.S. Pat. No. ♦Requires electrical poling in high field 3,747,120 strengths during manufacture ♦Epson Stylus ♦Tektronix ♦USSN 09/112,803 Electro- An electric field is used to activate ♦Low power consumption ♦Low maximum strain (approx. 0.01%) ♦Seiko Epson, Usui et strictive electrostriction in relaxor materials ♦Many ink types can be used ♦Large area required for actuator due to all JP 253401/96 such as lead lanthanum zirconate ♦Low thermal expansion low strain USSN 09/112,803 titanate (PLZT) or lead magnesium ♦Electric field strength ♦Response speed is marginal (˜10 μs) niobate (PMN). required (approx. 3.5 V/μm) ♦High voltage drive transistors required can be generated without ♦FuIl pagewidth print heads impractical difficulty due to actuator size ♦Does not require electrical poling Ferroelectric An electric field is used to induce a ♦Low power consumption ♦Difficult to integrate with electronics USSN 09/112,803 phase transition between the ♦Many ink types can be used ♦Unusual materials such as PLZSnT are antiferroelectric (AFE) and ♦Fast operation (<1 μs) required ferroelectric (FE) phase. Perovskite ♦Relatively high longitudinal ♦Actuators require a large area materials such as tin modified lead strain lanthanum zirconate titanate ♦High efficiency (PLZSnT) exhibit large strains of up ♦Electric field strength of to 1% associated with the AFE to FE around 3 V/μm can be phase transition. readily provided Electrostatic Conductive plates are separated by a ♦Low power consumption ♦Difficult to operate electrostatic USSN 09/112,787; plates compressible or fluid dielectric ♦Many ink types can be used devices in an aqueous environment 09/112,803 (usually air). Upon application of a ♦Fast operation ♦The electrostatic actuator will normally voltage, the plates attract each other need to be separated from the ink and displace ink, causing drop ♦Very large area required to achieve ejection. The conductive plates may high forces be in a comb or honeycomb ♦High voltage drive transistors may be structure, or stacked to increase the required surface area and therefore the force. ♦Full pagewidth print heads are not competitive due to actuator size Electrostatic A strong electric field is applied to ♦Low current consumption ♦High voltage required ♦1989 Saito et al, U.S. Pat. No. pull on ink the ink, whereupon electrostatic ♦Low temperature ♦May be damaged by sparks due to air 4,799,068 attraction accelerates the ink towards breakdown ♦1989 Miura et al, the print medium. ♦Required field strength increases as the U.S. Pat. No. 4,810,954 drop size decreases ♦Tone-jet ♦High voltage drive transistors required ♦Electrostatic field attracts dust Permanent An electromagnet directly attracts a ♦Low power consumption ♦Complex fabrication USSN 09/113,084; magnet permanent magnet, displacing ink ♦Many ink types can be used ♦Permanent magnetic material such as 09/112,779 electro- and causing drop ejection. Rare earth ♦Fast operation Neodymium Iron Boron (NdFeB) magnetic magnets with a field strength around ♦High efficiency required. 1 Tesla can be used. Examples are: ♦Easy extension from single ♦High local currents required Samarium Cobalt (SaCo) and nozzles to pagewidth print ♦Copper metalization should be used for magnetic materials in the heads long electromigration lifetime and low neodymium iron boron family resistivity (Nd)FeB, NdDyFeBNb, NdDyFeB, ♦Pigmented inks are usually infeasible etc) ♦Operating temperature limited to the Curie temperature (around 540 K.) Soft magnetic A solenoid induced a magnetic field ♦Low power consumption ♦Complex fabrication USSN 09/112,751; core electro- in a soft magnetic core or yoke ♦Many ink types can be used ♦Materials not usually present in a 09/113,097; 09/113,066; magnetic fabricated from a ferrous material ♦Fast operation CMOS fab such as NiFe, CoNiFe, or 09/112,779; 09/113,061; such as electroplated iron alloys such ♦High efficiency CoFe are required 09/112,816; 09/112,772; as CoNiFe [1], CoFe, or NiFe alloys. ♦Easy extension from single ♦High local currents required 09/112,815 Typically, the soft magnetic material nozzles to pagewidth print ♦Copper metalization should be used for is in two parts, which are normally heads long electromigration lifetime and low held apart by a spring. When the resistivity solenoid is actuated, the two parts ♦Electroplating is required attract, displacing the ink. ♦High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Lorenz force The Lorenz force acting on a current ♦Low power consumption ♦Force acts as a twisting motion USSN 09/113,099; carrying wire in a magnetic field is ♦Many ink types can be used ♦Typically, only a quarter of the 09/113,077; 09/112,818; utilized. ♦Fast operation solenoid length provides force in a 09/112,819 This allows the magnetic field to be ♦High efficiency useful direction supplied extemally to the print head, ♦Easy extension from single ♦High local currents required for example with rare earth nozzles to pagewidth print ♦Copper metalization should be used for permanent magnets. heads long electromigration lifetime and low Only the current carrying wire need resistivity be fabricated on the print-head, ♦Pigmented inks are usually infeasible simplifying materials requirements. Magneto- The actuator uses the giant ♦Many ink types can be used ♦Force acts as a twisting motion ♦Fischenbeck, U.S. Pat. No. striction magnetostrictive effect of materials ♦Fast operation ♦Unusual materials such as Terfenol-D 4,032,929 such as Terfenol-D (an alloy of ♦Easy extension from single are required ♦USSN 09/113,121 terbium, dysprosium and iron nozzles to pagewidth print ♦High local currents required developed at the Naval Ordnance heads ♦Copper metalization should be used for Laboratory, hence Ter-Fe-NOL). For ♦High force is available long electromigration lifetime and low best efficiency, the actuator should resistivity be pre-stressed to approx. 8 MPa. ♦Pre-stressing may be required Surface Ink under positive pressure is held in ♦Low power consumption ♦Requires supplementary force to effect ♦Silverbrook, EP 0771 tension a nozzle by surface tension. The ♦Simple construction drop separation 658 A2 and related reduction surface tension of the ink is reduced ♦No unusual materials ♦Requires special ink surfactants patent applications below the bubble threshold, causing required in fabrication ♦Speed may be limited by surfactant the ink to egress from the nozzle. ♦High efficiency properties ♦Easy extension from single nozzles to pagewidth print heads Viscosity The ink viscosity is locally reduced ♦Simple construction ♦Requires supplementary force to effect ♦Silverbrook, EP 0771 reduction to select which drops are to be ♦No unusual materials drop separation 658 A2 and related ejected. A viscosity reduction can be required in fabrication ♦Requires special ink viscosity patent applications achieved electrothermally with most ♦Easy extension from single properties inks, but special inks can be nozzles to pagewidth print ♦High speed is difficult to achieve engineered for a 100:1 viscosity heads ♦Requires oscillating ink pressure reduction. ♦A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is generated and ♦Can operate without a ♦Complex drive circuitry ♦1993 Hadimioglu et focussed upon the drop ejection nozzle plate ♦Complex fabrication al, EUP 550,192 region. ♦Low efficiency ♦1993 Elrod et al, EUP ♦Poor control of drop position 572,220 ♦Poor control of drop volume Thermoelastic An actuator which relies upon ♦Low power consumption ♦Efficient aqueous operation requires a ♦USSN 09/112,802; bend actuator differential thermal expansion upon ♦Many ink types can be used thermal insulator on the hot side 09/112,778; 09/112,815; Joule heating is used. ♦Simple planar fabrication ♦Corrosion prevention can be difficult 09/113,096; 09/113,068; ♦Small chip area required for ♦Pigmented inks may be infeasible, as 09/113,095; 09/112,808; each actuator pigment particles may jam the bend 09/112,809; 09/112,780; ♦Fast operation actuator 09/113,083; 09/112,793; ♦High efficiency 09/112,794; 09/113,128; ♦CMOS compatible voltages 09/113,127; 09/112,756; and currents 09/112,755; 09/112,754; ♦Standard MEMS processes 09/112,811; 09/112,812; can be used 09/112,813; 09/112,814; ♦Easy extension from single 09/112,764; 09/112,765; nozzles to pagewidth print 09/112,767; 09/112,768 heads High CTE A material with a very high ♦High force can be generated ♦Requires special material (e.g. PTFE) ♦USSN 09/112,778; thermoelastic coefficient of thermal expansion ♦Three methods of PTFE ♦Requires a PTFE deposition process, 09/112,815; 09/113,096; actuator (CTE) such as polytetrafluoro- deposition are under which is not yet standard in ULSI fabs 09/113,095; 09/112,808; ethylene (PTFE) is used. As high CTE development: chemical ♦PTFE deposition cannot be followed 09/112,809; 09/112,780; materials are usually non-conductive, vapor deposition (CVD), with high temperature (above 350° C.) 09/113,083; 09/112,793; a heater fabricated from a conductive spin coating, and evaporation processing 09/112,794; 09/113,128; material is incorporated. A 50 μm long ♦PTFE is a candidate for ♦Pigmented inks may be infeasible, as 09/113,127; 09/112,756; PTFE bend actuator with polysilicon low dielectric constant pigment particles may jam the bend 09/112,807; 09/112,806; heater and 15 mW power input can insulation in ULSI actuator 09/112,820 provide 180 μN force and 10 μm deflection. ♦Very low power consumption Actuator motions include: ♦Many ink types can be used Bend ♦Simple planar fabrication Push ♦Small chip area required Buckle for each actuator Rotate ♦Fast operation ♦High efficiency ♦CMOS compatible voltages and currents ♦Easy extension from single nozzles to pagewidth print heads Conductive A polymer with a high coefficient of ♦High force can be generated ♦Requires special materials ♦USSN 09/113,083 polymer thermal expansion (such as PTFE) is ♦Very low power development (High CTE conductive thermoelastic doped with conducting substances to consumption polymer) actuator increase its conductivity to about 3 ♦Many ink types can be used ♦Requires a PTFE deposition process, orders of magnitude below that of ♦Simple planar fabrication which is not yet standard in ULSI fabs copper. The conducting polymer ♦Small chip area required for ♦PTFE deposition cannot be followed expands when resistively heated. each actuator with high temperature (above 350° C.) Examples of conducting dopants ♦Fast operation processing include: ♦High efficiency ♦Evaporation and CVD deposition Carbon nanotubes ♦CMOS compatible voltages techniques cannot be used Metal fibers and currents ♦Pigmented inks may be infeasible, as Conductive polymers such as ♦Easy extension from single pigment particles may jam the bend doped polythiophene nozzles to pagewidth print actuator Carbon granules heads Shape memory A shape memory alloy such as TiNi ♦High force is available ♦Fatigue limits maximum number of ♦USSN 09/113,122 alloy (also known as Nitinol - Nickel (stresses of hundreds of cycles Titanium alloy developed at the MPa) ♦Low strain (1%) is required to extend Naval Ordnance Laboratory) is ♦Large strain is available fatigue resistance thermally switched between its weak (more than 3%) ♦Cycle rate limited by heat removal martensitic state and its high ♦High corrosion resistance ♦Requires unusual materiais (TiNi) stiffness austenic state. The shape of ♦Simple construction ♦The latent heat of transformation must the actuator in its martensitic state is ♦Easy extension from single be provided deformed relative to the austenic nozzles to pagewidth print ♦High current operation shape. The shape change causes heads ♦Requires pre-stressing to distort the ejection of a drop. ♦Low voltage operation martensitic state Linear Linear magnetic actuators include ♦Linear Magnetic actuators ♦Requires unusual semiconductor ♦USSN 09/113,061 Magnetic the Linear Induction Actuator (LIA), can be constructed with materials such as soft magnetic alloys Actuator Linear Permanent Magnet high thrust, long travel, and (e.g. CoNiFe ) Synchronous Actuator (LPMSA), high efficiency using planar ♦Some varieties also require permanent Linear Reluctance Synchronous semiconductor fabrication magnetic materials such as Actuator (LRSA), Linear Switched techniques Neodymium iron boron (NdFeB) Reluctance Actuator (LSRA), and ♦Long actuator travel is ♦Requires complex multi-phase drive the Linear Stepper Actuator (LSA). available circuitry ♦Medium force is available ♦High current operation ♦Low voltage operation BASIC OPERATION MODE Description Advantages Disadvantages Examples Actuator This is the simplest mode of ♦Simple operation ♦Drop repetition rate is usually limited ♦Thermal ink jet directly operation: the actuator directly ♦No external fields required to around 10 kHz. However, this is ♦Piezoelectric ink jet pushes ink supplies sufficient kinetic energy to ♦Satellite drops can be not fundamental to the method, but is ♦USSN 09/112,751; expel the drop. The drop must have a avoided if drop velocity is related to the refill method normally 09/112,787; 09/112,802; sufficient velocity to overcome the less than 4 m/s used 09/112,803; 09/113,097; surface tension. ♦Can be efficient, depending ♦All of the drop kinetic energy must be 09/113,099; 09/113,084; upon the actuator used provided by the actuator 09/112,778; 09/113,077; ♦Satellite drops usually form if drop 09/113,061; 09/112,816; velocity is greater than 4.5 m/s 09/112,819; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820 Proximity The drops to be printed are selected ♦Very simple print head ♦Requires close proximity betweeri the ♦Silverbrook, EP 0771 by some manner (e.g. thermally fabrication can be used print head and the print media or 658 A2 and related induced surface tension reduction of ♦The drop selection means transfer roller patent applications pressurized ink). Selected drops are does not need to provide the ♦May require two print heads printing separated from the ink in the nozzle energy required to separate alternate rows of the image by contact with the print medium or the drop from the nozzle ♦Monolithic color print heads are a transfer roller. difficult Electrostatic The drops to be printed are selected ♦Very simple print head ♦Requires very high electrostatic field ♦Silverbrook, EP 0771 pull on ink by some manner (e.g. thermally fabrication can be used ♦Electrostatic field for small nozzle 658 A2 and related induced surface tension reduction of ♦The drop selection means sizes is above air breakdown patent applications pressurized ink). Selected drops are does not need to provide the ♦Electrostatic field may attract dust ♦Tone-Jet separated from the ink in the nozzle energy required to separate by a strong electric field. the drop from the nozzle Magnetic pull The drops to be printed are selected ♦Very simple print head ♦Requires magnetic ink ♦Silverbrook, EP 0771 on ink by some manner (e.g. thermally fabrication can be used ♦Ink colors other than black are difficult 658 A2 and related induced surface tension reduction of ♦The drop selection means ♦Requires very high magnetic fields patent applications pressurized ink). Selected drops are does not need to provide the separated from the ink in the nozzle energy required to separate by a strong magnetic field acting on the drop from the nozzle the magnetic ink. Shutter The actuator moves a shutter to ♦High speed (>50 kHz) ♦Moving parts are required ♦USSN 09/112,818; block ink flow to the nozzle. The ink operation can be achieved ♦Requires ink pressure modulator 09/112,815; 09/112,808 pressure is pulsed at a multiple of the due to reduced refill time ♦Friction and wear must be considered drop ejection frequency. ♦Drop timing can be very ♦Stiction is possible accurate ♦The actuator energy can be very low Shuttered grill The actuator moves a shutter to ♦Actuators with small travel ♦Moving parts are required ♦USSN 09/113,066; block ink flow through a grill to the can be used ♦Requires ink pressure modulator 09/112,772; 09/113,096; nozzle. The shutter movement need ♦Actuators with small force ♦Friction and wear must be considered 09/113,068 only be equal to the width of the grill can be used ♦Stiction is possible holes. ♦High speed (>50 kHz) operation can be achieved Pulsed A pulsed magnetic field attracts an ♦Extremely low energy ♦Requires an external pulsed magnetic ♦USSN 09/112,779 magnetic pull ‘ink pusher’ at the drop ejection operation is possible field on ink pusher frequency. An actuator controls a ♦No heat dissipation ♦Requires special materials for both the catch, which prevents the ink pusher problems actuator and the ink pusher from moving when a drop is not to ♦Complex construction be ejected. AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples None The actuator directly fires the ink ♦Simplicity of construction ♦Drop ejection energy must be supplied ♦Most inkjets, drop, and there is no extemal field or ♦Simplicity of operation by individual nozzle actuator including other mechanism required. ♦Small physical size piezoelectric and thermal bubble. ♦USSN 09/112,751; 09/112,787; 09/112,802; 09/112,803; 09/113,097; 09/113,084; 09/113,078; 09/113,077; 09/113,061; 09/112,816; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820 Oscillating ink The ink pressure oscillates, ♦Oscillating ink pressure can ♦Requires extemal ink pressure ♦Silverbrook, EP 0771 pressure providing much of the drop ejection provide a refill pulse, oscillator 658 A2 and related (including energy. The actuator selects which allowing higher operating ♦Ink pressure phase and amplitude must patent applications acoustic drops are to be fired by selectively speed be carefully controlled ♦USSN 09/113,066; stimulation) blocking or enabling nozzles. The ♦The actuators may operate ♦Acoustic reflections in the ink chamber ♦09/112,818; 09/112,772; ink pressure oscillation may be with much lower energy must be designed for 09/112,815; 09/113,096; achieved by vibrating the print head, ♦Acoustic lenses can be used 09/113,068; 09/112,808 or preferably by an actuator in the to focus the sound on the ink supply. nozzles. Media The print head is placed in close ♦Low power ♦Precision assembly required ♦Silverbrook, EP 0771 proximity proximity to the print medium. ♦High accuracy ♦Paper fibers may cause problems 658 A2 and related Selected drops protrude from the ♦Simple print head ♦Cannot print on rough substrates patent applications print head further than unselected construction drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer roller Drops are printed to a transfer roller ♦High accuracy ♦Bulky ♦Silverbrook, EP 0771 instead of straight to the print ♦Wide range of print ♦Expensive 658 A2 and related medium. A transfer roller can also be substrates can be used ♦Complex construction patent applications used for proximity drop separation. ♦Ink can be dried on the ♦Tektronix hot melt transfer roller piezoelectric inkjet ♦Any of USSN 09/112,751; 09/112,787; 09/112,802; 09/112,803; 09/113,097; 09/113,099; 09/113,084; 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Electrostatic An electric field is used to accelerate ♦Low power ♦Field strength required for separation ♦Silverbrook, EP 0771 selected drops towards the print ♦Simple print head of small drops is near or above air 658 A2 and related medium. construction breakdown patent applications ♦Tone-Jet Direct A magnetic field is used to accelerate ♦Low power ♦Requires magnetic ink ♦Silverbrook, EP 0771 magnetic field selected drops of magnetic ink ♦Simple print head ♦Requires strong magnetic field 658 A2 and related towards the print medium. construction patent applications Cross The print head is placed in a constant ♦Does not require magnetic ♦Requires extemal magnet ♦USSN 09/113,099; magnetic field magnetic field. The Lorenz force in a materials to be integrated in ♦Current densities may be high, 09/112,819 current carrying wire is used to move the print head resulting in electromigration problems the actuator manufacturing process Pulsed A pulsed magnetic field is used to ♦Very low power operation ♦Complex print head construction ♦USSN 09/112,779 magnetic field cyclically attract a paddle, which is possible ♦Magnetic materials required in print pushes on the ink. A smali actuator ♦Small print headsize head moves a catch, which selectively prevents the paddle from moving. ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples None No actuator mechanical ♦Operational simplicity ♦Many actuator mechanisms have ♦Thermal Bubble amplification is used. The actuator insufficient travel, or insufficient force, Ink jet directly drives the drop ejection to efficiently drive the drop ejection ♦USSN 09/112,751; process. process 09/112,787; 09/113,099; 09/113,084; 09/112,819; 09/113,121; 09/113,122 Differential An actuator material expands more ♦Provides greater travel in a ♦High stresses are involved ♦Piezoelectric expansion on one side than on the other. The reduced print head area ♦Care must be taken that the materials ♦USSN 09/112,802; bend actuator expansion may be thermal, do not delaminate 09/112,778; 09/112,815; piezoelectric, magnetostrictive, or ♦Residual bend resulting from high 09/113,096; 09/113,068; other mechanism. The bend temperature or high stress during 09/113,095; 09/112,808; actuator converts a high formation 09/112,809; 09/112,780; force low travel actuator 09/113,083; 09/112,793; mechanism to high travel, 09/113,128; 09/113,127; lower force mechanism. 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820 Transient bend A trilayer bend actuator where the ♦Very good temperature ♦High stresses are involved ♦USSN 09/112,767; actuator two outside layers are identical. This stability ♦Care must be taken that the materials 09/112,768 cancels bend due to ambient ♦High speed, as a new drop do not delaminate temperature and residual stress. The can be fired before heat actuator only responds to transient dissipates heating of one side or the other. ♦Cancels residual stress of formation Reverse spring The actuator loads a spring. When ♦Better coupling to the ink ♦Fabrication complexity ♦USSN 09/113,097; the actuator is turned off, the spring ♦High stress in the spring 09/113,077 releases. This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator stack A series of thin actuators are stacked. ♦Increased travel ♦Increased fabrication complexity ♦Some piezoelectric This can be appropriate where ♦Reduced drive voltage ♦Increased possibility of short circuits ink jets actuators require high electric field due to pinholes ♦USSN 09/112,803 strength, such as electrostatic and piezoelectric actuators. Multiple Multiple smaller actuators are used ♦Increases the force available ♦Actuator forces may not add linearly, ♦USSN 09/113,061; actuators simultaneously to move the ink. from an actuator reducing efficiency 09/112,818; 09/113,096; Each actuator need provide only a ♦Multiple actuators can be 09/113,095; 09/112,809; portion of the force required. positioned to control ink 09/112,794; 09/112,807; flow accurately 09/112,806 Linear Spring A linear spring is used to transform a ♦Matches low travel actuator ♦Requires print head area for the spring ♦USSN 09/112,772 motion with small travel and high with higher travel force into a longer travel, lower force requirements motion. ♦Non-contact method of motion transformation Coiled A bend actuator is coiled to provide ♦Increases travel ♦Generally restricted to planar ♦USSN 09/112,815; actuator greater travel in a reduced chip area. ♦Reduces chip area implementations due to extreme 09/112,801; 09/112,811; ♦Planar implementations are fabrication difficulty in other 09/112,812 relatively easy to fabricate. orientations. Flexure bend A bend actuator has a small region ♦Simple means of increasing ♦Care must be taken not to exceed the ♦USSN 09/112,779; actuator near the fixture point, which flexes travel of a bend actuator elastic limit in the flexure area 09/113,068; 09/112,754 much more readily than the ♦Stress distribution is very uneven remainder of the actuator. The ♦Difficult to accurately model with actuator flexing is effectively finite element analysis converted from an even coiling to an angular bend, resulting in greater travel of the actuator tip. Catch The actuator controls a small catch. ♦Very 1ow actuator energy ♦Complex construction ♦USSN 09/112,779 The catch either enables or disables ♦Very small actuator size ♦Requires external force movement of an ink pusher that is ♦Unsuitable for pigmented inks controlled in a bulk manner. Gears Gears can be used to increase travel ♦Low force, low travel ♦Moving parts are required ♦USSN 09/112,818 at the expense of duration. Circular actuators can be used ♦Several actuator cycles are required gears, rack and pinion, ratchets, and ♦Can be fabricated using ♦More complex drive electronics other gearing methods can be used. standard surface MEMS ♦Complex construction processes ♦Friction, friction, and wear are possible Buckle plate A buckle plate can be used to change ♦Very fast movement ♦Must stay within elastic limits of the ♦S. Hirata et al, “An a slow actuator into a fast motion. It achievable materials for long device life Ink-jet Head Using Diaphragm can also convert a high force, low ♦High stresses involved Microactuator”, Proc. IEEE MEMS, travel actuator into a high travel, ♦Generally high power requirement Feb. 1996, pp 418-423. medium force motion. ♦USSN 09/113,096; 09/112,793 Tapered A tapered magnetic pole can increase ♦Linearizes the magnetic ♦Complex construction ♦USSN 09/112,816 magnetic pole travel at the expense of force. force/distance curve Lever A lever and fulcrum is used to ♦Matches low travel actuator ♦High stress around the fulcrum ♦USSN 09/112,755; transform a motion with small travel with higher travel 09/112,813; 09/112,814 and high force into a motion with requirements longer travel and lower force. The ♦Fulcrum area has no linear lever can also reverse the direction of movement, and can be used travel. for a fluid seal Rotary The actuator is connected to a rotary ♦High mechanical advantage ♦Complex construction ♦USSN 09/112,794 impeller impeller. A small angular deflection ♦The ratio of force to travel ♦Unsuitable for pigmented inks of the actuator results in a rotation of of the actuator can be the impeller vanes, which push the matched to the nozzle ink against stationary vanes and out requirements by varying the of the nozzle. number of impeller vanes Acoustic lens A refractive or diffractive (e.g. zone ♦No moving parts ♦Large area required ♦1993 Hadimioglu et al, plate) acoustic lens is used to ♦Only relevant for acoustic ink jets EUP 550,192 concentrate sound waves. ♦1993 Elrod et al, EUP 572,220 Sharp A sharp point is used to concentrate ♦Simple construction ♦Difficult to fabricate using standard ♦Tone-jet conductive an electrostatic field. VLSI processes for a surface ejecting point ink-jet ♦Only relevant for electrostatic ink jets ACTUATOR MOTION Description Advantages Disadvantages Examples Volume The volume of the actuator changes, ♦Simple construction in the ♦High energy is typically required to ♦Hewlett-Packard expansion pushing the ink in all directions. case of thermal ink jet achieve volume expansion. This leads Thermal Ink jet to thermal stress, cavitation, and ♦Canon Bubblejet kogation in thermal ink jet implementations Linear, normal The actuator moves in a direction ♦Efficient coupling to ink High fabrication complexity may be ♦USSN 09/112,751; to chip surface normal to the print head surface. The drops ejected normal to the required to achieve perpendicular 09/112,818; 09/112,772; nozzle is typically in the line of surface motion 09/113,084; 09/113,077; movement. 09/112,816 Parallel to The actuator moves parallel to the ♦Suitable for planar ♦Fabrication complexity ♦USSN 09/113,061; chip surface print head surface. Drop ejection fabrication ♦Friction 09/112,818; 09/112,772; may still be normal to the surface. ♦Stiction 09/112,754; 09/112,811; 09/112,812; 09/112,813 Membrane An actuator with a high force but ♦The effective area of the ♦Fabrication complexity ♦1982 Howkins U.S. Pat. No. push small area is used to push a stiff actuator becomes the ♦Actuator size 4,459,601 membrane that is in contact with the membrane area ♦Difficulty of integration in a VLSI ink. process Rotary The actuator causes the rotation of ♦Rotary levers may be used ♦Device complexity ♦USSN 09/113,097; some element, such a grill or to increase travel ♦May have friction at a pivot point 09/113,066; 09/112,818; impeller ♦Small chip area 09/112,794 requirements Bend The actuator bends when energized. ♦A very small change in ♦Requires the actuator to be made from ♦1970 Kyser et al U.S. Pat. No. This may be due to differential dimensions can be at least two distinct layers, or to have a 3,946,398 thermal expansion, piezoelectric converted to a large motion. thermal difference across the actuator ♦1973 Stemme U.S. Pat. No. expansion, magnetostriction, or other 3,747,120 form of relative dimensional change. ♦09/112,802; 09/112,778; 09/112,779; 09/113,068; 09/112,780; 09/113,083; 09/113,121; 09/113,128; 09/113,127; 09/113,128; 09/112,754; 09/112,811; 09/112,812 Swivel The actuator swivels around a central ♦Allows operation where the ♦Inefficient coupling to the ink motion ♦USSN 09/113,099 pivot. This motion is suitable where net linear force on the there are opposite forces applied to paddle is zero opposite sides of the paddle, e.g. ♦Small chip area Lorenz force. requirements Straighten The actuator is normally bent, and ♦Can be used with shape ♦Requires careful balance of stresses to ♦USSN 09/113,122; straightens when energized. memory alloys where the ensure that the quiescent bend is 09/112,755 austenic phase is planar accurate Double bend The actuator bends in one direction ♦One actuator can be used to ♦Difficult to make the drops ejected by ♦USSN 09/112,813; when one element is energized, and power two nozzles. both bend directions identical. 09/112,814; 09/112,764 bends the other way when another ♦Reduced chip size. ♦A small efficiency loss compared to element is energized. ♦Not sensitive to ambient equivalent single bend actuators. temperature Shear Energizing the actuator causes a ♦Can increase the effective ♦Not readily applicable to other actuator ♦1985 Fishbeck U.S. Pat. No. shear motion in the actuator material. travel of piezoelectric mechanisms 4,584,590 actuators Radial The actuator squeezes an ink ♦Relatively easy to fabricate ♦High force required ♦1970 Zoltan U.S. Pat. No. constriction reservoir, forcing ink from a single nozzles from glass ♦Inefficient 3,683,212 constricted nozzle. tubing as macroscopic ♦Difficult to integrate with VLSI structures processes Coil/uncoil A coiled actuator uncoils or coils ♦Easy to fabricate as a planar ♦Difficult to fabricate for non-planar ♦USSN 09/112,815; more tightly. The motion of the free VLSI process devices 09/112,808; 09/112,811; end of the actuator ejects the ink. ♦Small area required, ♦Poor out-of-plane stiffness 09/112,812 therefore low cost Bow The actuator bows (or buckles) in the ♦Can increase the speed of ♦Maximum travel is constramed ♦USSN 09/112,819; middle when energized. travel ♦High force required 09/113,096; 09/112,793 ♦Mechanically rigid Push-Pull Two actuators control a shutter. One ♦The structure is pinned at ♦Not readily suitable for ink jets which ♦USSN 09/113,096 actuator pulls the shutter, and the both ends, so has a high directly push the ink other pushes it. out-of-plane rigidity Curl inwards A set of actuators curl inwards to ♦Good fluid flow to the ♦Design complexity ♦USSN 09/113,095; reduce the volume of ink that they region behind the actuator 09/112,807 enclose. increases efficiency Curl outwards A set of actuators curl outwards, ♦Relatively siinple ♦Relatively large chip area ♦USSN 09/112,806 pressurizing ink in a chamber construction surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes enclose a volume of ♦Righ efficiency ♦High fabrication complexity ♦USSN 09/112,809 ink. These simultaneously rotate, ♦Small chip area ♦Not suitable for pigmented inks reducing the volume between the vanes. Acoustic The actuator vibrates at a high ♦The actuator can be ♦Large area required for efficient ♦1993 Hadimioglu et al, vibration frequency. physically distant from the operation at useful frequencies EUP 550,192 ink ♦Acoustic coupling and crosstalk ♦1993 Elrod et al, EUP ♦Complex drive circuitry 572,220 ♦Poor control of drop volume and position None In various ink jet designs the actuator ♦No moving parts ♦Various other tradeoffs are required to ♦Silverbrook, EP 0771 658 does not move. eliminate moving parts A2 and related patent applications ♦Tone-jet NOZZLE REFILL METHOD Description Advantages Disadvantages Examples Surface This is the normal way that ♦Fabrication simplicity ♦Low speed ♦Thermal ink jet tension ink jets are refilled. After the ♦Operational simplicity ♦Surface tension force relatively small ♦Piezoelectric ink jet actuator is energized, it typically compared to actuator force ♦09/112,751; 09/113,084; returns rapidly to its normal position. ♦Long refill time usually 09/112,779; 09/112,816; This rapid return sucks in air through dominates the total repetition 09/112,819; 09/113,095; the nozzle then exerts a small force rate 09/112,809; 09/112,780; restoring the meniscus to a minimum area. 09/113,083; 09/113,121; This force refills the nozzle. 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Shuttered Ink to the nozzle chamber is ♦High speed ♦Requires common ink pressure ♦USSN 09/113,066; oscillating ink provided at a pressure that oscillates ♦Low actuator energy, as the oscillator 09/112,818; 09/112,772; pressure at twice the drop ejection frequency. actuator need only open or ♦May not be suitable for pigmented inks 09/112,815; 09/113,096; When a drop is to be ejected, the close the shutter, instead of 09/113,068; 09/112,808 shutter is opened for 3 half cycles: ejecting the ink drop drop ejection, actuator return, and refill. The shutter is then closed to prevent the nozzle chamber emptying during the next negative pressure cycle. Refill actuator After the main actuator has ejected a ♦High speed, as the nozzle is ♦Requires two independent actuators per ♦USSN 09/112,778 drop a second (refill) actuator is actively refilled nozzle energized. The refill actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive ink The ink is held a slight positive ♦High refill rate, therefore a ♦Surface spill must be prevented ♦Silverbrook, EP 0771 658 pressure pressure. After the ink drop is high drop repetition rate is ♦Highly hydrophobic print head A2 and related patent ejected, the nozzle chamber fills possible surfaces are required applications quickly as surface tension and ink ♦Alternative for: USSN pressure both operate to refill the 09/112,751; 09/112,787; nozzle 09/112,802; 09/112,803; 09/113,097; 09/113,099; 09/113,084; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,819; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description Advantages Disadvantages Examples Long inlet The ink iniet channel to the nozzle ♦Design simplicity ♦Restricts refill rate ♦Thermal ink jet channel chamber is made long and relatively ♦Operational simplicity ♦May result in a relatively large chip ♦Piezoelectric ink jet narrow, relying on viscous drag to ♦Reduces crosstalk area ♦USSN 09/112,807; reduce inlet back-flow. ♦Only partially effective 09/112,806 Positive ink The ink is under a positive pressure, ♦Drop selection and ♦Requires a method (such as a nozzle ♦Silverbrook, EP 0771 658 pressure so that in the quiescent state some of separation forces can be rim or effective hydrophobizing, or A2 and related patent the ink drop already protrudes from reduced both) to prevent flooding of the applications the nozzle. ♦Fast refill time ejection surface of the print head. ♦Possible operation of This reduces the pressure in the the following: nozzle chamber which is required to ♦USSN 09/112,751; eject a certain volume of ink. The 09/112,787; 09/112,802; reduction in chamber pressure results 09/112,803; 09/113,097; in a reduction in ink pushed out 09/113,099; 09/113,084; through the inlet. 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,816; 09/112,819; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; Baffle One or more baffles are placed in the ♦The refill rate is not as ♦Design complexity ♦HP Thermal Ink Jet inlet ink flow. When the actuator is restricted as the long inlet ♦May increase fabrication complexity ♦Tektronix energized, the rapid ink movement method. (e.g. Tektronix hot melt Piezoelectric piezoelectric ink jet creates eddies which restrict the flow ♦Reduces crosstalk print heads). through the inlet. The slower refill process is unrestricted, and does not result in eddies. Flexible flap In this method recently disclosed by ♦Significantly reduces back- ♦Not applicable to most ink jet ♦Canon restricts inlet Canon, the expanding actuator flow for edge-shooter configurations (bubble) pushes on a flexible flap thermal ink jet devices ♦Increased fabrication complexity that restricts the inlet. ♦Inelastic deformation of polymer flap results in creep over extended use Inlet filter A filter is located between the ink ♦Additional advantage of ink ♦Restricts refill rate ♦USSN 09/112,803; inlet and the nozzle chamber. The filtration ♦May result in complex construction 09/113,061; 09/113,083; filter has a multitude of small holes ♦Ink filter may be fabricated 09/112,793; 09/113,128; or slots, restricting ink flow. The with no additional process 09/113,127 filter also removes particles which steps may block the nozzle. Small inlet The ink inlet channel to the nozzle ♦Design simplicity ♦Restricts refill rate ♦USSN 09/112,787; compared to chamber has a substantially smaller ♦May result in a relatively large chip 09/112,814; 09/112,820 nozzle cross section than that of the nozzle, area resulting in easier ink egress out of ♦Only partially effective the nozzle than out of the inlet. Inlet shutter A secondary actuator controls the ♦Increases speed of the ink- ♦Requires separate refill actuator and ♦USSN 09/112,778 position of a shutter, closing off the jet print head operation drive circuit ink inlet when the main actuator is energized. The inlet is The method avoids the problem of ♦Back-flow problem is ♦Requires careful design to minimize ♦USSN 09/112,751; located behind inlet back-flow by arranging the ink- eliminated the negative pressure behind the paddle 09/112,802; 09/113,097; the ink- pushing surface of the actuator 09/113,099; 09/113,084; pushing between the inlet and the nozzle. 09/112,779; 09/113,077; surface 09/112,816; 09/112,819; 09/112,809; 09/112,780; 09/113,121; 09/112,794; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,765; 09/112,767; 09/112,768 Part of the The actuator and a wall of the ink ♦Significant reductions in ♦Small increase in fabrication ♦USSN 09/113,084; actuator chamber are arranged so that the back-flow can be achieved complexity 09/113,095; 09/113,122; moves to shut motion of the actuator closes off the ♦Compact designs possible 09/112,764 off the inlet inlet. Nozzle In some configurations of ink jet, ♦Ink back-flow problem is ♦None related to ink back-flow on ♦SiIverbrook, EP 0771 658 actuator does there is no expansion or movement eliminated actuation A2 and related patent not result in of an actuator which may cause ink applications ink back-flow back-flow through the inlet. ♦Valve-jet ♦Tone-jet NOZZLE CLEARING METHOD Description Advantages Disadvantages Examples Normal nozzle All of the nozzles are fired ♦No added complexity on the ♦May not be sufficient to displace dried ♦Most ink jet systems firing periodically, before the ink has a print head ink ♦USSN 09/112,751; chance to dry. When not in use the 09/112,787; 09/112,802; nozzles are sealed (capped) against 09/112,803; 09/113,097; air. The nozzle firing is usually 09/113,099; 09/113,084; performed during a special clearing 09/112,778; 09/112,779; cycle, after first moving the print 09/113,077; 09/113,061; head to a cleaning station. 09/112,816; 09/112,819; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112821 Extra power to In systems which heat the ink, but do ♦Can be highly effective if ♦Requires higher drive voltage for ♦Silverbrook, EP 0771 658 ink heater not boil it under normal situations, the heater is adjacent to the clearing A2 and related patent nozzle clearing can be achieved by nozzle ♦May require larger drive transistors applications over-powering the heater and boiling ink at the nozzle. Rapid The actuator is fired in rapid ♦Does not require extra drive ♦Effectiveness depends substantially ♦May be used with: USSN succession of succession. In some configurations, circuits on the print head upon the configuration of the ink jet 09/112,751; 09/112,787; actuator this may cause heat build-up at the ♦Can be readily controlled nozzle 09/112,802; 09/112,803; pulses nozzle which boils the ink, clearing and initiated by digital logic 09/113,097; 09/113,099; the nozzle. In other situations, it may 09/113,084; 09/112,778; cause sufficient vibrations to 09/112,779; 09/113,077; dislodge clogged nozzles. 09/112,816; 09/112,819; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Extra power to Where an actuator is not normally ♦A simple solution where ♦Not suitable where there is a hard limit ♦May be used with: USSN ink pushing driven to the limit of its motion, applicable to actuator movement 09/112,802; 09/112,778; actuator nozzle clearing may be assisted by 09/112,819; 09/113,095; providing an enhanced drive signal 09/112,780; 09/113,083; to the actuator. 09/113,121; 09/112,793; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Acoustic An ultrasonic wave is appiied to the ♦A high nozzle clearing ♦High implementation cost if system ♦USSN 09/113,066; resonance ink chamber. This wave is of an capability can be achieved does not already include an acoustic 09/112,818; 09/112,722; appropriate amplitude and frequency ♦May be implemented at actuator 09/112,815; 09/113,096; to cause sufficient force at the nozzle very low cost in systems 09/113,068; 09/112,808 to clear blockages. This is easiest to which already include achieve if the ultrasonic wave is at a acoustic actuators resonant frequency of the ink cavity. Nozzle A microfabricated plate is pushed ♦Can clear severely clogged ♦Accurate mechanical alignment is ♦Silverbrook, EP 0771 658 clearing plate against the nozzles. The plate has a nozzles required A2 and related patent post for every nozzle. A post moves ♦Moving parts are required applications through each nozzle, displacing ♦There is risk of damage to the nozzles dried ink. ♦Accurate fabrication is required Ink pressure The pressure of the ink is ♦May be effective where ♦Requires pressure pump or other ♦May be used with ink jets pulse temporarily increased so that ink other methods cannot be pressure actuator covered by USSN streams from all of the nozzles. This used ♦Expensive 09/112,751; 09/112,787; may be used in conjunction with ♦Wasteful of ink 09/112,802; 09/112,803; actuator energizing. 09/113,097; 09/113,099; 09/113,084; 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Print head A flexible ‘blade’ is wiped across the ♦Effective for planar print ♦Difficult to use if print head surface is ♦Many ink jet systems wiper print head surface. The blade is head surfaces non-planar or very fragile usually fabricated from a flexible ♦Low cost ♦Requires mechanical parts polymer, e.g. rubber or synthetic ♦Blade can wear out in high volume elastomer. print systems Separate ink A separate heater is provided at the ♦Can be effective where ♦Fabrication complexity ♦Can be used with many boiling heater nozzle although the normal drop e- other nozzle clearing ink jets covered by USSN ection mechanism does not require it. methods cannot be used 09/112,751; 09/112,787; The heaters do not require individual ♦Can be implemented at no 09/112,802; 09/112,803; drive circuits, as many nozzles can additional cost in some 09/113,097; 09/113,099; be cleared simultaneously, and no ink jet configurations 09/113,084; 09/113,066; imaging is required. 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09.113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages Examples Electroformed A nozzle plate is separately ♦Fabrication simplicity ♦High temperatures and pressures are ♦Hewlett Packard nickel fabricated from electroformed nickel, required to bond nozzle plate Thermal Ink jet and bonded to the print head chip. ♦Minimum thickness constraints ♦Differential thermal expansion Laser ablated Individual nozzle holes are ablated ♦No masks required ♦Each hole must be individually formed ♦Canon Bubblejet or drilled by an intense UV laser in a nozzle ♦Can be quite fast ♦Special equipment required ♦1988 Sercel et al., polymer plate, which is typically a polymer ♦Some control over nozzle ♦Slow where there are many thousands SPIE, Vol. 998 such as polyimide or polysulphone profile is possible of nozzles per print head Excimer Beam ♦Equipment required is ♦May produce thin burrs at exit holes Applications, pp. 76-83 relatively low cost ♦1993 Watanabe et al., U.S. Pat. No. 5,208,604 Silicon micro- A separate nozzle plate is ♦High accuracy is attainable ♦Two part construction ♦K. Bean, IEEE machined micromachined from single crystal ♦High cost Transactions on silicon, and bonded to the print head ♦Requires precision alignment Electron Devices, wafer. ♦Nozzles may be clogged by adhesive Vol. ED-25, No. 10, 1978, pp 1185-1195 ♦Xerox 1990 Hawkins et al., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries are drawn from ♦No expensive equipment ♦Very small nozzle sizes are difficult to ♦1970 Zoltan U.S. Pat. No. capillaries glass tubing. This method has been required form 3,683,212 used for making individual nozzles, ♦Simple to make single ♦Not suited for mass production but is difficult to use for bulk nozzles manufacturing of print heads with thousands of nozzles. Monolithic, The nozzle plate is deposited as a ♦Hjgh accuracy (<1 μm) ♦Requires sacrificial layer under the ♦Silverbrook, EP 0771 658 surface micro- layer using standard VLSI deposition ♦Monolithic nozzle plate to form the nozzle A2 and related patent machined techniques. Nozzles are etched in the ♦Low cost chamber applications using VLSI nozzle plate using VLSI lithography ♦Existing processes can be ♦Surface may be fragile to the touch ♦USSN 09/112,751; lithographic and etching. used 09/112,787; 09/112,803; processes 09/113,077; 09/113,061; 09/112,815; 09/113,096; 09/113,095; 09/112,809; 09/113,083; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820 Monolithic, The nozzle plate is a buried etch stop ♦High accuracy (<1 μm) ♦Requires long etch times ♦USSN 09/112,802; etched in the wafer. Nozzle chambers are ♦Monolithic ♦Requires a support wafer 09/113,097; 09/113,099; through etched in the front of the wafer, and ♦Low cost 09/113,084; 09/113,066; substrate the wafer is thinned from the back ♦No differential expansion 09/112,778; 09/112,779; side. Nozzles are then etched in the 09/112,818; 09/112,816; etch stop layer. 09/112,772; 09/112,819; 09/113,068; 09/112,808; 09/112,780; 09/113,121; 09/113,122 No nozzle Various methods have been tried to ♦No nozzles to become ♦Difficult to control drop position ♦Ricoh 1995 Sekiya et al plate eliminate the nozzles entirely, to clogged accurately U.S. Pat. No. 5,412,413 prevent nozzle clogging. These ♦Crosstalk problems ♦1993 Hadimioglu et al include thermal bubble mechanisms EUP 550,192 and acoustic lens mechanisms ♦1993 Elrod et al EUP 572,220 Trough Each drop ejector has a trough ♦Reduced manufacturing ♦Drop firing direction is sensitive to ♦USSN 09/112,812 through which a paddle moves. complexity wicking. There is no nozzle plate. ♦Monolithic Nozzle slit The elimination of nozzle holes and ♦No nozzles to become ♦Difficult to control drop position. ♦1989 Saito et al instead of replacement by a slit encompassing clogged accurately U.S. Pat. No. 4,799,068 individual many actuator positions reduces ♦Crosstalk problems nozzles nozzle clogging, but increases crosstalk due to ink surface waves DROP EJECTION DIRECTION Description Advantages Disadvantages Examples Edge Ink flow is along the surface of the ♦Simple construction ♦Nozzles limited to edge ♦Canon Bubblejet 1979 (‘edge chip, and ink drops are ejected from ♦No silicon etching required ♦High resolution is difficult Endo et al GB patent shooter’) the chip edge. ♦Good heat sinking via ♦Fast color printing requires one print 2,007,162 substrate head per color ♦Xerox heater-in-pit ♦Mechanically strong 1990 Hawkins et al ♦Ease of chip handing U.S. Pat. No. 4,899,181 ♦Tone-jet Surface Ink flow is along the surface of the ♦No bulk silicon etching ♦Maximum ink flow is severely ♦Hewlett-Packard TIJ (‘roof shooter’) chip, and ink drops are ejected from required restricted 1982 Vaught et al the chip surface, normal to the plane ♦Silicon can make an U.S. Pat. No. 4,490,728 of the chip. effective heat sink ♦USSN 09/112,787, ♦Mechanical strength 09/113,077; 09/113,061; 09/113,095; 09/112,809 Through chip, Ink flow is through the chip, and ink ♦High ink flow ♦Requires bulk silicon etching ♦Silverbrook, EP 0771 658 forward drops are ejected from the front ♦Suitable for pagewidth print A2 and related (‘up shooter’) surface of the chip. ♦High nozzle packing patent applications density therefore low ♦USSN 09/112,803; manufacturing cost 09/112,815; 09/113,096; 09/113,083; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Through chip, Ink flow is through the chip, and ink ♦High ink flow ♦Requires wafer thinning ♦USSN 09/112,751; reverse drops are ejected from the rear ♦Suitable for pagewidth print ♦Requires special handling during 09/112,802; 09/113,097; (‘down surface of the chip. ♦High nozzle packing manufacture 09/113,099; 09/113,084; shooter’) density therefore low 09/113,066; 09/112,778; manufacturing cost 09/112,779; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/113,068; 09/112,808; 09/112,780; 09/113,121; 09/113,122 Through Ink flow is through the actuator, ♦Suitable for piezoelectric ♦Pagewidth print heads require several ♦Epson Stylus actuator which is not fabricated as part of the print heads thousand connections to drive circuits ♦Tektronix hot melt same substrate as the drive ♦Cannot be manufactured in standard piezoelectric ink jets transistors. CMOS fabs ♦Complex assembly required INK TYPE Description Advantages Disadvantages Examples Aqueous, dye Water based ink which typically ♦Environmentally friendly ♦Slow drying ♦Most existing ink jets contains: water, dye, surfactant, ♦No odor ♦Corrosive ♦USSN 09/112,751; humectant, and biocide. ♦Bleeds on paper 09/112,787; 09/112,802; Modern ink dyes have high water- ♦May strikethrough 09/112,803; 09/113,097; fastness, light fastness ♦Cockles paper 09/113,099; 09/113,084; 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 ♦Silverbrook, EP 0771 658 A2 and related patent applications Aqueous, Water based ink which typically ♦Environmentally friendly ♦Slow drying ♦USSN 09/112,787; pigment contains: water, pigment, surfactant, ♦No odor ♦Corrosive 09/112,803; 09/112,808; humectant, and biocide. ♦Reduced bleed ♦Pigment may clog nozzles 09/113,122; 09/112,793; Pigments have an advantage in ♦Reduced wicking ♦Pigment may clog actuator 09/113,127 reduced bleed, wicking and ♦Reduced strikethrough mechanisms ♦Silverbrook, EP 0771 658 strikethrough. ♦Cockles paper A2 and related patent applications ♦Piezoelectric ink-jets ♦Thermal ink jets (with significant restrictions) Methyl Ethyl MEK is a highly volatile solvent ♦Very fast drying ♦Odorous ♦USSN 09/112,751; Ketone (MEK) used for industrial printing on ♦Prints on various substrates ♦Flammable 09/112,787; 09/112,802; difficult surfaces such as aluminum such as metals and plastics 09/112,803; 09/113,097; cans. 09/113,099; 09/113,084; 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Alcohol Alcohol based inks can be used ♦Fast drying ♦Slight odor ♦USSN 09/112,751; (ethanol, 2- where the printer must operate at ♦Operates at sub-freezing ♦Flammable 09/112,787; 09/112,802; butanol, and temperatures below the freezing temperatures 09/112,803; 09/113,097; others) point of water. An example of this is ♦Reduced paper cockle 09/113,099; 09/113,084; in-camera consumer photographic ♦Low cost 09/113,066; 09/112,778; printing. 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Phase change The ink is solid at room temperature, ♦No drying time- ink ♦High viscosity ♦Tektronix hot melt (hot melt) and is melted in the print head before instantly freezes on the ♦Printed ink typically has a ‘waxy’ feel piezoelectric ink jets jetting. Hot melt inks are usually print medium ♦Printed pages may ‘block’ ♦1989 Nowak U.S. Pat. No. wax based, with a melting point ♦Almost any print medium ♦Ink temperature may be above the 4,820,346 around 80° C.. After jetting the ink can be used curie point of permanent magnets ♦USSN 09/112,751; freezes almost instantly upon ♦No paper cockle occurs ♦Ink heaters consume power 09/112,787; 09/112,802; contacting the print medium or a ♦No wicking occurs ♦Long warm-up time 09/112,803; 09/113,097; transfer roller. ♦No bleed occurs 09/113,099; 09/113,084; ♦No strikethrough occurs 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Oil Oil based inks are extensively used ♦High solubility medium for ♦High viscosity: this is a significant ♦USSN 09/112,751; in offset prititing. They have some dyes limitation for use in inkjets, which 09/112,787; 09/112,802; advantages in improved ♦Does not cockle paper usually require a low viscosity. Some 09/112,803; 09/113,097; characteristics on paper (especially ♦Does not wick through short chain and multi-branched oils 09/113,099; 09/113,084; no wicking or cockle). Oil soluble paper have a sufficiently low viscosity. 09/113,066; 09/112,778; dies and pigments are required. ♦Slow drying 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Microemulsion A microemulsion is a stable, self ♦Stops ink bleed ♦Viscosity higher than water ♦USSN 09/112,751; forming emulsion of oil, water, and ♦High dye solubility ♦Cost is slightly higher than water based 09/112,787; 09/112,802; surfactant. The characteristic drop ♦Water, oil, and amphiphilic ink 09/112,803; 09/113,097; size is less than 100 nm, and is soluble dies can be used ♦High surfactant concentration required 09/113,099; 09/113,084; determmed by the preferred ♦Can stabilize pigment (around 5%) 09/113,066; 09/112,778; curvature of the surfactant. suspensions 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 

What is claimed is:
 1. A method of manufacturing an ink jet printhead which includes: providing a substrate; depositing a doped layer on the substrate and etching said layer to create an array of nozzles on the substrate with a nozzle chamber in communication with each nozzle; and utilising planar monolithic deposition, lithographic and etching processes to create a magnetically responsive shutter for openably closing each nozzle chamber, an electromagnetically operable device which acts on the shutter for opening and closing the shutter on demand for controlling ejection of ink from the nozzle and an urging means for urging the shutter to its rest position.
 2. A method of manufacturing an ink jet printhead as claimed in claim 1 wherein multiple ink jet printheads are formed simultaneously on the substrate.
 3. A method of manufacturing an ink jet printhead as claimed in claim 1 wherein said substrate is a silicon wafer.
 4. A method of manufacturing an ink jet printhead as claimed in claim 1 wherein integrated drive electronics are formed on the same substrate.
 5. A method of manufacturing an ink jet printhead as claimed in claim 4 wherein said integrated drive electronics are formed using a CMOS fabrication process.
 6. A method of manufacturing an ink jet printhead as claimed in claim 1 wherein ink is ejected from said substrate normal to said substrate.
 7. A method of manufacture of a drop on demand ink jet printhead arrangement including a series of nozzle chambers, said method comprising the steps of: (a) utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon; (b) etching a nozzle chamber aperture in said electrical circuitry layer in communication with a nozzle chamber in said semiconductor wafer; (c) depositing a first sacrificial layer which fills said nozzle chamber; (d) depositing and etching a first inert material layer, said first inert material layer including a grill structure over said nozzle chamber aperture and vias for electrical interconnection of subsequent layers with said electrical circuitry layer; (e) depositing and etching a first conductive material layer, said conductive material layer including a series of lower electrical coil portions interconnected with said electrical circuitry layer; (f) depositing and etching a second inert material layer over said first conductive material layer, said second inert material layer including predetermined vias for interconnection of said first conductive material layer with subsequent layers; (g) depositing and etching a second sacrificial layer including etching a mould for a solenoid, a fixed magnetic pole, and a linear spring anchor; (h) depositing and etching a high saturation flux material layer to form said series of fixed magnetic poles, a linear spring, said linear spring anchor and a displaceable shutter for openably closing its associated nozzle chamber and on which the linear spring acts for biasing the shutter to a rest position; (i) depositing and etching a third inert material layer over said high saturation flux material layer, said third inert material layer including predetermined vias for interconnection of lower conductive material layers with subsequent conductive material layers; (j) depositing and etching a second conductive material layer, said second conductive material layer including side electrical coil portions surrounding said series of fixed magnetic poles interconnected with said first conductive material layer, (k) depositing and etching a third conductive material layer, said third conductive material layer including a top electrical coil portion interconnected with said second conductive material layer; (l) depositing and etching a top inert material layer as a corrosion barrier; (m) back etching said wafer to said epitaxial layer; (n) etching a nozzle aperture in said epitaxial layer; and (o) etching away said sacrificial layer.
 8. A method as claimed in claim 7 wherein said epitaxial layer is utilized as an etch stop in said step (b).
 9. A method as claimed in claim 7 wherein said step (b) comprises a crystallographic etch of said wafer.
 10. A method as claimed in claim 7 wherein said high saturation flux material comprises substantially a cobalt nickel iron alloy.
 11. A method as claimed in claim 9 wherein said conductive layers comprise substantially copper.
 12. A method as claimed in claim 7 wherein said inert material layers comprise substantially silicon nitride.
 13. A method as claimed in claim 7 further including the step of depositing corrosion barriers over portions of said arrangement so as to reduce corrosion effects.
 14. A method as claimed in claim 7 wherein said wafer comprises a double side polished CMOS wafer.
 15. A method as claimed in claim 7 wherein at least said steps (m) and (o) are also utilized to simultaneously separate said wafer into separate printheads. 